How do children organize their knowledge about the world? Recently there has been a shift in the treatment of concepts, from traditional views assuming that concepts can be characterized by superficial features, to "theory" views treating concepts as embedded in commonsense explanatory frameworks. The finding that children's concepts are tied to theories is especially striking, as it runs counter to a previously widely accepted view of children's concepts as "perceptually bound." In contrast, preschoolers expect category members to share nonobvious similarities, even in the face of salient perceptual dissimilarities, and judge non-visible internal parts to be especially crucial to the identity and functioning of an item. In a sense, very young children act as if members of a category share an underlying "essence". In the prior funding period, my collaborators and I addressed three goals: (1) We charted how essentialist beliefs are expressed in natural language by young children (ages 2-4 years), and how natural language expressions of essentialism are interpreted by young children. Specifically, this work focused on generic noun phrases as a vital means of essentialist expression. (2) We examined how concepts are influenced by two core essentialist components: unobservable causes and ontologies. (3) We sought to reconcile essentialism with the traditional view of children as focused on perceptual aspects of the world, by clarifying the conditions that lead to different profiles of performance. The competing renewal builds on the past work by examining the mechanisms by which generic language links to categorization and essentialist reasoning. Specifically, I address three focal issues: [unreadable] the conceptual implications of generic language during childhood. [unreadable] how generics are expressed and understood across structurally distinct languages and different cultural contexts. [unreadable] the links between generic concepts and essentialist beliefs (including nativism, causal reasoning, and inductive reasoning). The proposed research uses naturalistic language analyses and experimental studies with children 3-10 years of age to address these questions. Specifically, the proposal has three aims: Part 1 charts how generic language influences children's category formation, memory, and reasoning. Part 2 examines the use and comprehension of generic language in two languages that are structurally very different from one another and from English (Quechua and Spanish). Part 3 examines how the distinction between generic kinds and other sorts of categories reflects and influences children's essentialist reasoning. Altogether, these 27 studies will provide converging and precise evidence regarding the links among concepts, language, and theory construction in early childhood.